fix docs errors

docs/assets/js/docs.js

@@ -42,6 +42,11 @@ $(function() {
     footerHeight           = $('.docs-footer').outerHeight(false);
     toolbarToggle          = $('.js-docs-component-toolbar');
 
+    // exit if no device
+    if (!device.length) {
+      return;
+    }
+
     // Device placement
     if (windowWidth >= 768) {
       device.initialLeft   = device.offset().left;
@@ -179,5 +184,7 @@ $(function() {
   };
 
   $(window).on('load resize', initialize);
-  $(window).on('load', function () { new FingerBlast('.device-content'); });
+  $(window).on('load', function () {
+    window.FingerBlast && (new FingerBlast('.device-content'));
+  });
 });